I have a number of C610IP and C530IP base stations (local), all provisioned manually. The settings are fairly straight forward if you are familiar with SIP. What i did discover is that the server IP (again I'm using locally), may have to be put in three places...Domain, Proxy Server and Registration server. This all depends on the menu as I'm assuming yours it is, at least, similar to the ones on my sets. Since it should support STUN, (mine do), you may be able to use remotely. Remember each extension used must be set to use a different port number, local or remote.